Self-closing (and self-opening) gates are in common use, particularly in situations which require increased safety. For example, it is mandatory in some countries to provide self-closing gates for swimming pool fences, to prevent unsupervised access by small children in the event that other persons have forgotten to close the gate. Similarly, self-closing gates are often employed in households to prevent toddlers from accessing stairways and other potentially hazardous areas.
Gates of this type generally include a helical spring-loaded hinge which produces a torque to bias the hinge towards the closed (or open, as the case may be) position. A problem which arises in relation to such gates is that they vary in dimension and weight, and so the spring tension in the hinge must be adjusted accordingly in order to have the gate close or open at appropriate speed.
One solution to the problem, as proposed by Australian patent no. 666491, is to provide a coupling element connected to the spring. The coupling element includes a head portion with a circular top section and a hexagonal intermediate section which engages a matching hexagonal engagement surface in an aperture of the spring housing. The top section includes a slot to accommodate a screwdriver. When it is desired to adjust the spring tension, the person installing the gate inserts a screwdriver into the slot and applies pressure to disengage the coupling element so that it can be turned to a different orientation. A disadvantage of this arrangement is that it requires the simultaneous application of a linear force along the spring axis and a rotational force about the spring axis. This is a relatively unnatural movement which can cause inconvenience to the installer. Use of a screwdriver can also cause inconvenience in that the knuckles on the installer's hand may be obstructed by the hinge or the gate to which it is mounted.
It is therefore desirable to provide a hinge which has adjustable tension, but which is easier to install and adjust than known hinges of the type described above.